关于电场与磁场的变换关系及其相对性

本文避开张量概念，由洛仑兹力公式的协变性，来讨论电磁场的变换关系．进而说明电磁场的相对性，并通过一具体事例讨论不同参考系中电磁场的来源．     

电磁场和电磁波的教学之我见

电磁场和电磁波的教学之我见贵州瓮安监狱子校费开伦在高中物理课本第二册“电磁场和电磁波”一节中，介绍了电磁场的基本理论——一麦克斯韦理论．教材中选编了法拉第定律和经麦克斯韦修正后的安培定律．以及麦克斯韦预言一．因为原理论是高度数学化的方程组，非常抽象．...     

分界面运动时电磁场的边值关系

直接利用电磁场场量的相对论变换，得出了运动分界面处电磁场的边值关系．     

电磁场──物质的基本形式之一

电磁场是物质的基本形式之一，它无需电荷激发，而是自然界固有的；电荷只是为了描写电磁场而引入的一过渡量．并由此提出了一个计算电子电能的设想．     

关于电源能量的传输问题

通过对进入电阻和电容器内的能流的计算，分析了电源能量的传输问题．结果表明，电源的能量是通过电磁场传输出去的，通电电线的作用是提供所需的电磁场．     

电磁铸造中的基础理论和电磁场研究

液态金属在电磁场、温度场、流场等复杂的三维场综合作用下受电磁力约束成型，电磁场分布直接关系到铸造的成败，电磁场的研究是电磁铸造技术研究的重要基础．文章综合概述了电磁铸造的基础理论、电磁场主要研究方法、研究内容、现状，重点介绍了采用数学模拟方法进行电磁场研究的几个具有代表性的研究成果，以及基于目前的研究现状展望今后的研究发展方向。     

电磁流动演示实验设计

让液体流动起来，通常是利用加压的方式，如水泵抽水．但如果液体中有离子，离子在电磁场作用下定向移动，从而引起液体的流动，这种方式称为电磁流动，或电磁泵．本文设计了电磁流动的演示仪，将不易观察到的带电粒子在电磁场中受力运动情况清晰展现出来．     

电磁灶的电磁辐射

为了消除人们在使用电磁灶时对健康的担心，根据麦克斯韦方程和电磁场辐射理论经过计算电磁转换线圈产生的辐射电磁场强度，得出辐射电磁场的强度与线圈中心越远越小；θ越大越强；电磁转换线圈半径越大；电流的频率越高越大的结论．     

用洛仑兹力的冲量式巧解粒子在电磁场中运动的极值问题

<正>带电粒子在电磁场中的运动问题是近几年高考的热点问题．运动的轨迹由过去的直线或圆周运动逐渐变化为复杂的曲线运动．求解带电粒子在电磁场中运动的极值更是学生感到困难的问题．笔者在教学过程中总结出应用洛伦兹力的冲量式解决这类问题，特别简捷明了．     

电磁场在生产生活科技实际中的应用

电现象和磁现象与人类有着密切的联系．例如我们生活生产中使用的电话、电视、发电机、电动机，现代科学研究中使用的电流表、计算机、质谱仪、回旋加速器等，其工作原理大都是高中所学的电磁场的知识．电磁场的应用确实很多，本文着重讨论由电场和磁场对带电粒子的控制作用，如加速、偏转等，这类问题具有强烈的时代气息和丰富的科技信息，是锤炼综合分析能力、发散创新思维、理论联系实际、学以致用的好素材．下面示例说明．     

无轴承电机悬浮控制系统的设计

无轴承电机是利用磁悬浮轴承和交流电机结构的相似性,将产生磁悬浮力的磁悬浮轴承绕组置入电机定子,省去了专门的磁悬浮轴承．通过对转矩绕组和悬浮力绕组的解耦控制,使电机的转子同时具有产生转矩和自悬浮的功能．无轴承电机能够实现高速、无摩擦等优良性能,是当前研究的热点之一,无轴承电机悬浮控制系统设计是该研究的关键．本文介绍了无轴承电机悬浮控制的基本原理,设计了基于转矩绕组转子磁场定向的悬浮控制系统．     

A First Course in Electrical Engineering

This article describes the introductory two-semester course in electrical engineering that has been developed over a period of five years at Princeton University. The aims of the course are to provide an introduction to the field of electrical engineering via the basic concepts of electricity and magnetism (which are developed through Maxwell's equations in the integral form), to apply these concepts in developing the fundamentals of energy conversion and circuit theory, and to carry forward, in a continuous and integrated way, a modern treatment of network analysis. Thus, the treatment proceeds from field ideas to circuits and physical apparatus, and to their mathematical models. With the circuit relations formulated, attention turns to the analysis of networks, starting with network topology and extending through pole-zero ideas. The treatment stops just short of the Laplace transform. This course is intended to serve as a foundation for subsequent courses such as electronic circuits, energy conversion, and advanced network analysis and synthesis, and has been developed with the purpose of providing the student with a unifying point of view for these varied topics.     

稀土永磁同步电动机调速的研究

本讨论稀土永磁同步电动机空载反电动势R的取值是电磁设计的关键所在．它关系列永磁同步电动机运行性能的效率和功率因数的大小，采用变压变频(VVVF)交流调遣系统，可以保持电源的频率f与电源的电压U以及与空载反电动势E0的对应关系，结合稀土永磁同步电动机的设计值和试验实测值。阐明变压变频(VVVF)交流调速系统是稀土永磁同步电动机的最佳调速方法。     

Contributions of Maxwell to electromagnetism

Maxwell, one of the greatest physicists of the nineteenth century, was the founder of a consistent theory of electromagnetism. However, it must be noted that significant discoveries and intelligent efforts of Coulomb, Volta, Ampére, Oersted, Faraday, Gauss, Poisson, Helmholtz and others preceded the work of Maxwell, enhancing a partial understanding of the connection between electricity and magnetism. Maxwell, by sheer logic and physical understanding of the earlier discoveries completed the unification of electricity and magnetism. The aim of this article is to describe Maxwell's contribution to electricity and magnetism. P V Panat is Professor of Physics at the Pune University, His main research interests are condensed matter theory and quantum optics.     

永磁同步电动机状态方程研究和起动过程仿真

由于永磁同步电动机与普通三相异步电动机相比，起动过程较为复杂，可利用坐标变换的PARK方程，推导出永磁同步电动机的状态方程，最后利用四阶龙格-库塔法，编写样机的起动过程仿真程序，并得出仿真结果。     

MAGNETISM TEACHING SEQUENCES BASED ON AN INDUCTIVE APPROACH FOR FIRST-YEAR THAI UNIVERSITY SCIENCE STUDENTS

The study investigated the impact on student motivation and understanding of magnetism of teaching sequences based on an inductive approach. The study was conducted in large lecture classes. A pre- and post-Conceptual Survey of Electricity and Magnetism was conducted with just fewer than 700 Thai undergraduate science students, before and after being taught the concepts, in three academic years. For 2005 and 2006, overall, the students had a better understanding of concepts associated with electricity, but a majority of the students seemed not to understand magnetism after the teaching. Drawing on these findings, the teaching sequences of the magnetism topic were developed, and then implemented in the academic year 2007. The teaching sequences included demonstrations and visuals to help students infer rules and theories for themselves (inductive method). In addition, interactive notes, information on historical science discoveries about magnetic phenomenon, questions, student discussions, and magnetism problems were used to support student learning during lectures. Students in the academic year 2007 performed significantly better after the teaching. In addition, the students had a positive perception towards the teaching sequences, which allowed them to be involved more actively during lectures.     

对电场、磁场及电磁场的再认识

在大学物理教材中普遍存在着把电场和磁场分离开来的一个不合理的认识,并由此派生出了一些不合实际的说法。文章指出,电磁波的传播过程和电磁感应现象并不简单地是电生磁、磁生电的过程,电场和磁场并非独立的两种物质,而是一种特殊物质(即电磁场)的二种属性或二种表现形式。     

Using the History of Electricity and Magnetism to Enhance Teaching

In the process of developing our modern understandingof electricity, magnetism and electromagnetism, ourpredecessors carried out experiments which are readilyreplicable in the classroom. Their understanding ofthe phenomena concerned followed a similar path tothat followed by modern students as they discover theconcepts of charge, conservation of charge, the natureof electric and magnetic fields and how electricity and magnetism interact. This paper willdescribe the historical development of these ideasincluding some of the experiments and discussionswhich can allow students to correctly form theseconcepts.     

发展中的自旋电子学

自旋电子学是一门最新发展起来的涉及磁学、电子学以及信息学的交叉学科。自旋电子器件与普通半导体电子器件相比具有不挥发、低功耗和高集成度等优点。磁学、电子学和信息学的结合有望产生出自旋场效应晶体管、自旋发光二极管、调制器及用于量子计算、量子通信等装置的新型器件。     

静电磁学中的牛顿第三定律和超距作用

澄清了静电磁学中关于超距作用的某些观点,确认在静电磁相互作用场合不必引入场。指出牛顿第三定律的通常公式表示有不足之处,该定律与超距作用也有差别,提出了"刚体的相互作用定律",并据此分析了两电偶极子和两通电线圈情形时的相互作用。